Ophthalmic solution comprising glycogen

ABSTRACT

The present invention relates to humectant and lubricant solution for ophthalmic use based on a glycogen polysaccharide.

This invention relates to a humectant and lubricant solution forophthalmic use based on a glycogen polysaccharide.

It is known that the instillation of humectant and lubricant solutionsinto the eye is indicated in some circumstances. These solutions are allthe more useful if they mimic the functions of natural tear fluid.

This type of humectant and lubricant solution has therefore been giventhe name of “artificial tears”, even when the capacity to mimic naturaltear fluid is not entirely satisfactory.

Artificial tears are used, for example, to alleviate the symptoms of drykeratoconjunctivitis, exposure-induced keratopathies and othersituations resulting in dry eye syndrome. In addition to this artificialtears are useful to wearers of contact lenses, particularly in the caseof hard lenses.

One of the properties required from artificial tears is that they shouldproduce a sensation of well-being and freshness which lasts for asufficient length of time.

In the past it was considered that in order to achieve this objectiveartificial tears should have a high viscosity, and this was achieved byadding polymers such as cellulose esters, polyethylene glycol,polystyrene sulphonate or polyvinyl acid.

However, such artificial tears do not satisfactorily mimic theproperties of natural tear fluid which, as is known, has a rather lowviscosity (between 1 and 6 cP) [J. M. Tiffany, “InternationalOphthalmology”, 15, 371-376, 1991 H. Botner, T. Waaler and O. Wik, “DrugDevelopment and Industrial Pharmacy”, 16(5), 755-768, 1990].

In addition to this it has been shown that a viscosity greater than 20cP is generally regarded as being uncomfortable on account of eyelidmovement (J. I. Greaves, O. Olejnik and C. G. Wilson, “Pharma.Sciences”, 2(1 13-33, 1992). Also, viscosities in excess of 40-50 cP cancause occlusion of the tear duct and give the patient a continualsensation of having a foreign body in the eye (M. Amorosa, “Principi diTecnica Farmaceutica”, (Principles of pharmaceutical technology), 399,1983).

U.S. Pat. No. 4,039,662 proposes that this disadvantage should beovercome through a low viscosity ophthalmic solution containing dextranor arabinogalactan together with benzylalkonium chloride. In particular,the abovementioned patent specifies that the polysaccharide componentalone without benzylalkonium chloride is incapable of remaining adsorbedonto the cornea for a sufficiently long period (column 3, lines 9-13).In explanation of this behaviour it is hypothesised that thepolysaccharide particles described in the aforesaid patent combine insolution with the benzylalkonium chloride by electrostatic attraction.This seems to form a complex having an electron charge which causes themacromolecule to be adsorbed onto the surface of the cornea (column 3,lines 19-37).

Furthermore, it is known from the literature that aqueous solutions ofdextran have an osmotic pressure which is much greater than that ofnatural tears (F. J. Holly and E. D. Esquivel “Colloid Osmotic Pressureof Artificial Tears”, Journal of Ocular Pharmacology, 1, 327-336, 1985).Despite the fact that this contrasts with the principle according towhich tho physical proportions of artificial tears should be as similaras possible to those of natural tears, Holly et al. specificallyattribute the greater acceptance of dextran-based artificial tears bypatients to the said greater oncotic pressure.

Now it has been surprisingly found that glycogen polysaccharides providean ophthalmic solution of low viscosity and low oncotic pressure andexert a pleasing refreshing, lubricating and humectant effect on thecornea even in the absence of benzylalkonium chloride (Table I).

Therefore, it is an object of this invention to provide the use of aglycogen polysaccharide, as an active ingredient, substantially free ofnitrogen when determined by the Kjeldahl method, for the manufacture ofophthalmic sterile aqueous solution useful as an artificial tear.

Preferably the glycogen polysaccharide Is prepared according to patentEP-B-0 654 048.

It has also been found that, in addition to being characterized by along residence time In the eye, aqueous solutions of glycogenpolysaccharides can be filtered to 0.2 microns, and can thus providesterile solutions up to a concentration of 12% (w/v). In addition tothis, these solutions have a low viscosity and a low oncotic pressure.

Typically the quantity of glycogen polysaccharide in the ophthalmicsolution according to this invention is of from 0.1 to 12% (w/v).

Preferably it is of from 1 to 6% (w/v). Even more preferably it is offrom 2 to 4% (w/v).

Typically the ophthalmic solution according to this invention has aviscosity of between 1 and 9 cP. Preferably it has a viscosity between 2and 7 cP. Even more preferably, it has a viscosity between 2 and 6 cP.

Typically, the ophthalmic solution according to this Invention has anoncotic pressure of less than 5 mmHg. Preferably it has an oncoticpressure of less than 3 mmHg.

The ophthalmic solution according to this Invention may also containother conventional ingredients such as: antioxidants, buffers, compoundsto render the solution isotonic with tear fluid, stabilising agents,colouring agents and the like.

Typical examples of antioxidants are cysteine, ascorbic acid andtaurine. The latter is also particularly preferred on account of itsanti-free radical properties.

The quantity of antioxidant in the ophthalmic solution according to thisinvention will vary widely according to the preselected composition. Inthe specific case of taurine, the quantity is preferably of from 0.1 to0.6% (w/v) and, even more preferably, from 0.2 to 0.4% (w/v).

Typical examples of buffers are borate, bicarbonate, acetate andphosphate buffers, and their quantities will be selected so as toregulate the pH of the ophthalmic solution according to this inventionbetween 5 and 8. Preferably the buffer will be a phosphate buffer andthe pH of the ophthalmic solution according to the invention will beadjusted between 6.5 and 7.5.

Typical examples of compounds suitable for ensuring that the ophthalmicsolution according to this invention is isotonic with natural tear fluidare glycerine, sodium chloride and mannitol.

The quantities of these in the ophthalmic solution according to thisinvention will vary widely according to the preselected composition. Inthe particular case of mannitol, the quantity is preferably of from 0.5to 3% (w/v). Even more preferably it is of from 1.5% to 2% (w/v).

The composition according to this invention may also contain one or morepreservatives selected from the group comprising benzylalkoniumchloride, thimerosal, methyl parabenes, ethyl parabenes, propylparabenes and butyl parabenes.

The glycogen polysaccharide used in the examples below was extractedfrom Mytilus edulis or Mytilus gallus provincialis using the methoddescribed in EP-B-0 654 048 and had the following characteristics:

C: 44.44%

N: absent⁽¹⁾

reducing sugars⁽²⁾: absent

[α]_(D) ²⁰: 198±1.0 (c=1, water)

mean surface tension⁽³⁾:

3% aqueous solution at 25° C.: 66.29 mN/m

6% aqueous solution at 25° C.: 61.04 mN/m

3% aqueous solution at 37° C.: 59.19 mN/m

6% aqueous solution at 7° C.: 58.20 mN/m

contact angle with glass⁽⁴⁾ at ambient temperature (the comparison testwith water yielded a result of 42°):

3% aqueous solution: 32°

6% aqueous solution: 18°.

Notes:

⁽¹⁾ determined by the Kjeldahl method,

⁽²⁾ determined in accordance with F. D. Snell and Snell, “ColorimetricMethod of Analysis” N.Y., 1954, Vol. III, pag. 204,

⁽³⁾determined using a Lauda tensiometer,

⁽⁴⁾determined using a contact angle measuring device of the Face ContactAngle Meter, Kyowa Kaimenkagaki Co. Ltd., Nordtest type.

The following examples are intended to illustrate this invention withoutlimiting it in any way.

EXAMPLE 1 Preparation of an Ophthalmic Solution Containing a GlycogenPolysaccharide (Solution A)

Components Quantity (g) glycogen polysaccharide 3 D-mannitol 1.8 taurine0.3 monobasic sodium phosphate H₂O 0.2 dibasic sodium phosphate 12 H₂O1.5 distilled water q.s.p. 100 ml 

The abovementioned ophthalmic solution was prepared by dissolving theabovementioned components in the prescribed quantity of water at 18-25°C. The product was then filtered using a 0.22 μm filter to sterilise thepreparation.

The solution prepared in this way (Solution A) was subdivided into 0.4ml doses in single-use phials having a capacity of 1 ml. The solutionprepared in this way had the following properties:

pH 7.18 osmolarity⁽⁵⁾ 272 density⁽⁶⁾ (g/ml) at 25° C. 1.024 density⁽⁶⁾(g/ml) at 37° C. 1.016 viscosity⁽⁷⁾ (cP) 5 oncotic pressure⁽⁸⁾ (mmHg)1.7 sterility sterile mean surface tension⁽³⁾ (m/Nm) at 25° C. 61.80 at37° C. 61.90 Notes: ⁽⁵⁾determined using the Knauer Automatic Osmometerapparatus, ⁽⁶⁾determined using the Ken Da-310 M Mettler - Toledodensimeter, ⁽⁷⁾determined using a Mettler Rheomat Rm-180 rheometer,⁽⁸⁾determined using the Osmomat 050 Colloid Osmometer apparatus from theGonotec company,

Under the same conditions the oncotic pressure of a 3% w/w solution ofdextran was 16.4 mmHg.

EXAMPLE 2 Preparation of Solution B

Working in a manner similar to that described in Example 1 above, asecond solution was prepared and comprised:

Components Quantity (g) glycogen polysaccharide 3 mannitol 1.8 sodiumchloride 0.070 phosphate buffer pH 7, 1-7.4 distilled water q.s.p. 100ml The solution prepared in this way had the following characteristics:sterility sterile oncotic pressure⁽⁸⁾ (mmHg) 1.7 mean surface tension⁽³⁾m/Nm at 25° C. 61.43 at 37° C. 60.02 Notes: ⁽³⁾determined as in note⁽³⁾above. ⁽⁸⁾determined as in note⁽⁸⁾ above.

EXAMPLE 3 Preparation of an Ophthalmic Solution Containing a GlycogenPolysaccharide (Solution C)

Operating in a manner similar to that described in Example 1 above athird solution was prepared and comprised:

Components Quantity (g) glycogen polysaccharide 3 D-mannitol 1.8 taurine0.3 monobasic sodium phosphate H₂O 0.2 dibasic sodium phosphate 12 H₂O1.5 distilled water q.s.p. 50 ml   The solution prepared in this way(Solution C) had the following characteristcs: pH 7.30 density⁽⁶⁾(g/ml)at 20° C. 1.02252 sterility sterile mean surface tension⁽³⁾ (m/Nm)at 25° C. 72.81 ± 1.86 at 37° C. 69.97 ± 0.39 methyl- poly- paraffinrabbit glass acrylate ethylene wax teflon cornea contact angle at 25°C.⁽⁴⁾: 12.3 ± 1.9 60.9 ± 4.1 45.3 ± 5.7 94.3 ± 8.5 58.2 ± 6.0 40.1 ±13.0 contact angle at 37° C.⁽⁴⁾: 16.1 ± 3.3 60.2 ± 1.9 57.5 ± 7.0 95.6 ±4.0 65.3 ± 7.5 38.8 ± 12.9 Notes: ⁽³⁾determined by the method ofFerguson and Kenney (1932) [Tiffany J.M., Winter N., Bliss G., “Curr.Eye Res.”, 8, 507-515, 1989], ⁽⁴⁾determined by the procedure of Tiffany(1990) [Tiffany J.M., “Acta Ophtalmol”, 68, 182-187, 1990],⁽⁶⁾determined using the Ken Da-310 M Mettler-Toledo densimeter.

EXAMPLE 4 Preparation of solution E

Operating in a manner similar to that described in Example 1 above afourth solution was prepared and comprised:

Components Quantity (g) glycogen polysaccharide 1 D-mannitol 1.8 taurine0.3 monobasic sodium phosphate H₂O 0.2 dibasic sodium phosphate 12 H₂O1.5 distilled water q.s.p. 50 ml   The solution prepared in this way(Solution C) had the following characteristcs: pH 7.32 density⁽⁶⁾ (g/ml)at 20° C. 1.01602 sterility sterile mean surface tension⁽³⁾ (m/Nm) at25° C. 72.94 ± 0.61 at 37° C. 70.08 ± 0.22 methyl- poly- paraffin rabbitglass acrylate ethylene wax teflon cornea contact angle at 25° C.⁽⁴⁾:11.3 ± 2.3 44.3 ± 55.6 ± 4.3 78.4 ± 2.6 67.9 ± 4.0 43.4 ± 14.2 10.7contact angle at 37° C.⁽⁴⁾: 13.9 ± 4.0 51.3 ± 7.9 39.3 ± 5.8 88.7 ± 7.560.2 ± 19.8 ± 7.7  12.9 Notes: ⁽³⁾determined by the method of Fergusonand Kenney (1932) [Tiffany J.M., Winter N., Bliss G., “Curr. Eye Res.”,8, 507-515, 1989], ⁽⁴⁾determined by the procedure of Tiffany (1990)[Tiffany J.M., “Acta Ophtalmol”, 68, 182-187, 1990], ⁽⁶⁾determined usingthe Ken Da-310 M Mettler-Toledo densimeter.

EXAMPLE5 Preparation of Solution F

Operating in a manner similar to that described in Example 1 above afifth solution was prepared and comprised:

Components Quality (g) glycogen polysaccharide 6 D-mannitol 1.8 taurine0.3 monobasic sodium phosphate H₂O 0.2 dibasic sodium phosphate 12 H₂O1.5 distilled water q.s.p. 50 ml   The solution prepared in this way(Solution F) had the following characteristcs: pH 7.38 density⁽⁶⁾ (g/ml)at 20° C. 1.03173 sterility sterile mean surface tension⁽³⁾ (m/Nm) at25° C. 73.76 ± 0.91 at 37° C. 73.66 ± 0.74 methyl- poly- paraffin rabbitglass acrylate ethylene wax teflon cornea contact angle at 25° C.⁽⁴⁾:10.7 ± 2.1 60.4 ± 4.9 65.6 ± 6.9 99.9 ± 5.2 80.7 ± 6.7 98.9 ± 7.6 contact angle at 37° C.⁽⁴⁾: 17.6 ± 3.7 66.8 ± 2.7 52.8 ± 4.1 95.3 ± 3.681.7 ± 28.8 ± 10.8 11.2 Notes: ⁽³⁾determined by the method of Fergusonand Kenney (1932) [Tiffany J.M., Winter N., Bliss G., “Curr. Eye Res.”,8, 507-515, 1989], ⁽⁴⁾determined by the procedure of Tiffany (1990)[Tiffany J.M., “Acta Ophtalmol”, 68, 182-187, 1990], ⁽⁶⁾determined usingthe Ken Da-310 M Mettler-Toledo densimeter.

EXAMPLE 6 Preparation of Solution G

Operating in a manner similar to that described in Example 1 above asixth solution was prepared and comprised:

Components Quantity (g) glycogen polysaccharide 9 D-mannitol 1.8 taurine0.3 monobasic sodium phosphate H₂O 0.2 dibasic sodium phosphate 12 H₂O1.5 distilled water q.s.p. 50 ml   The solution prepared in this way(Solution G) had the following characteristcs: pH 7.27 density⁽⁶⁾ (g/ml)at 20° C. 1.04122 sterility sterile mean surface tension⁽³⁾ (m/Nm) at25° C. 74.37 ± 0.26 at 37° C. 72.63 ± 0.95 methyl- poly- paraffin rabbitglass acrylate ethylene wax teflon cornea contact angle at 25° C.⁽⁴⁾:12.8 ± 2.2 55.8 ± 4.1 54.3 ± 5.2 100.3 ± 3.0 87.3 ± 1.9 35.5 ± 9.9contact angle at 37° C.⁽⁴⁾: 15.2 ± 3.3 54.0 ± 3.1 59.8 ± 4.6  94.4 ± 1.576.3 ± 4.6 20.7 ± 4.3 Notes: ⁽³⁾determined by the method of Ferguson andKenney (1932) [Tiffany J.M., Winter N., Bliss G., “Curr. Eye Res.”, 8,507-515, 1989], ⁽⁴⁾determined by the procedure of Tiffany (1990)[Tiffany J.M., “Acta Ophtalmol”, 68, 182-187, 1990], ⁽⁶⁾determined usingthe Ken Da-310 M Mettler-Toledo densimeter.

Test 1

A double blind experiment was performed with Solution A, using theophthalmic solution Dacriosol™ from the Alcon company (Solution D),containing dextran (0.1%) and hydroxypropylmethylcellulose (0.3%) asactive ingredients, as the comparison preparation.

The experiment was performed on 11 healthy subjects of which 2 wereaffected by mild reddening of both eyes as a result of frequent computeruse, while 1 had reddening, again of both eyes, as a result of incipientrhinitis of an allergic nature.

One drop (equal to approximately 0.05 ml) of Solution A was instilledinto the left eye of each individual and one drop of Solution D into theright eye.

10-15 minutes after application the individuals were asked to describetheir sensations on a card, putting a cross on a continuous 90 mm linewhich started from a beginning (0—total absence of feeling) to an end(maximum or marked feeling). The distance of the cross from the startexpressed in millimetres constituted the score for that sensation.

The following parameters were taken into consideration:

a) sensation of wellbeing in the eyes,

b) sensation of freshness in the eyes,

c) sensation of wetness,

d) viscosity,

e) burning,

f) pain,

g) lachrymation,

h) sensation of the presence of a foreign body,

i) blurred vision, and

j) reddening of the conjunctive.

It will be noted from Tables I and II that both the solutions are welltolerated and that after an initial stage in which no individualreported any differences in sensation, after some 5-10 minutes SolutionA proved to induce a greater sensation of wellbeing, freshness andwetness and a lesser sensation of viscosity and lachrymation with aconsequent lesser sensation of the presence of a foreign body andblurring. This subjective assessment was confirmed in measurements ofthe viscosities of the two preparations (2.02 cP for Solution A and 7.6cP for Solution D). The three individuals affected by reddening of theeyes manifested a more marked reduction in this reddening in the case ofSolution A.

The above experiment was extended to a further 23 individuals. Hereagain the following parameters were taken into consideration:

a) sensation of wellbeing in the eyes,

b) sensation of freshness in the eyes,

c) sensation of wetness,

d) viscosity,

e) burning,

f) pain,

g) lachrymation,

h) sensation of the presence of a foreign body,

i) blurred vision, and

j) reddening of the conjunctiva.

This experiment yielded results similar to Tables I and II.

TABLE I Effects of Solution A after a single application No. EyeWellbeing Freshness Wetness Viscosity Burning Pain Lachrymation Foreignbody Blurring Reddening 1 L 2.5 5.1 3.0 0.5 0 0 0 0 0 0 2 L 1.5 3.9 3.86.2 0 0 0 0 0 0 * 3 L 1.0 3.7 1.0 0 0 0 0 0 0 0 4 L 2.8 2.8 2.8 0.5 0 00.4 0 0 0 5 L 0.3 0.3 0 0.8 0 0 0 0 0 0 6 L 7.7 7.7 7.9 0 0 0 0 0 0 0 7L 7.3 7.3 7.2 0 0 0 0 0 0 0 * 8 L 4.0 4.0 4.0 0 0 0 0 0 0 0 9 L 6.5 6.59.0 6.7 0 0 0 0 0 0 ** 10 L 6.0 6.1 5.5 0 0 0 0 0 0 0 11 L 6.2 6.7 4.6 00 0 1.9 0 0 0 Mean 4.2 4.9 4.4 1.3 0.0 0.0 0.2 0.0 0.0 0.0 ± 2.68 2.232.83 2.55 0.00 0.00 0.57 0.00 0.00 0.00 * Slight reduction inpre-existing reddening ** Marked reduction in pre-existing reddening

TABLE II Effects of Solution D after a single application No. EyeWellbeing Freshness Wetness Viscosity Burning Pain Lachrymation Foreignbody Blurring Reddening 1 R 2.8 3.7 5.7 0.4 0 0 1.5 0 0 0 2 R 4.5 4.64.6 1.8 0 0 0 0 0 0 * 3 R 1.0 1.9 0.9 6.8 0 0 0 0.5 2.8 0 4 R 2.8 2.75.2 6.9 0 0 0.5 0 3 0 5 R 1.7 1.5 0 0 0 0 0 0 0 0 6 R 4.8 8.0 8.0 0 1.00 1.1 0 0 0 * 7 R 3.0 2.9 2.9 7.7 0 0 0 0 0 0 8 R 4.0 1.7 0.9 0 0 0 0 00 0 * 9 R 6.5 1.5 0.0 1.6 0 0 0 0 0 0 10 R 6.1 8.1 7.0 0.7 0.7 0.7 1.40.9 0.7 0 11 R 1.1 1.1 2.8 1.3 6.7 0 1.7 2.7 0 0 Mean 3.5 3.4 3.5 2.50.8 0.1 0.6 0.4 0.6 0.0 ± 1.88 2.51 2.83 3.07 2.00 0.21 0.71 0.83 1.160.00 * Slight reduction in pre-existing reddening

What is claimed is:
 1. A method of lubricating an eye comprisingadministering a composition which comprises a glycogen polysaccharide,as an active ingredient, and a opthalmically acceptable carrier, whereinsaid glycogen polysaccharide is substantially free of nitrogen asdetermined by the Kjeldahl method.
 2. The method of claim 1, whereinsaid glycogen polysaccharide is in an amount of from 0.1 to 12%weight/volume.
 3. The method of claim 2, wherein said glycogenpolysaccharide is in an amount of from 1 to 6% weight/volume.
 4. Themethod of claim 3, wherein said glycogen polysaccharide is in an amountof from 2 to 4% weight/volume.
 5. The method of claim 1, wherein saidcomposition further comprises an antioxidant.
 6. The method of claim 5,wherein said antioxidant is taurine.
 7. The method of claim 1, whereinsaid composition further comprises an agent capable of regulatingisotonicity.
 8. The method of claim 6, wherein said agent capable ofregulating isotonicity is mannitol.
 9. The method of claim 1, whereinthe pH of said composition is from 5 to
 8. 10. The method of claim 9,wherein the pH of said composition is from 6.5 to 7.5.
 11. The method ofclaim 1, wherein said composition has a viscosity of from 1 to 9 cP. 12.The method of claim 2, wherein said composition has an oncotic pressureof not more than 5 mm Hg.
 13. The method of claim 12, wherein saidcomposition has an oncotic pressure of not more than 3 mm Hg.
 14. Amethod of lubricating an eye, comprising: administering a compositionwhich comprises a glycogen polysaccharide, as an active agent, and anopthalmically acceptable carrier, wherein said glycogen polysaccharideis substantially free of nitrogen as determined by the Kjeldahl methodand which has an oncotic pressure of not more than 5 mmHg.